Device and method for removing the jacket from cliché rollers in printing machines

ABSTRACT

Device for the substitution of a cliché-jacket from a cliché cylinder in a printing machine or the like wherein said cylinder ( 1 ) is connected to a motor ( 3 ) driving it into rotation about its longitudinal axis and is provided with radial holes connected with an air inlet ( 7 ), the latter being apt to be connected with a compressed air supply ( 6 ) by means of a delivery means ( 8 ), device characterized in that it comprises automatic means sensing the position of said air inlet ( 7 ) relative to said delivery means ( 8 ) and automatic means for positioning said air inlet ( 7 ) and said delivery means in a reciprocal coupling position, said automatic sensing and positioning means being connected to a programmable electronic unit (E) which, when said air inlet ( 7 ) and said delivery means ( 8 ) are coaxial, drives said coupling and switches on an on-off valve ( 60 ) which, on a side, is connected to said compressed air supply ( 6 ) and, on the other side, is connected to said delivery means ( 8 ).

The present invention relates to a device and a method for removing thejacket from cliché rollers in printing machines. In particular, even ifnot exclusively, the present device and method are destined to machinesof the type used for making prints on paper webs or plies for theproduction of kitchen paper rolls, toilette rolls and the like.

It is known that the printing machines of the above-mentioned type, alsoknown as flexographic printing machines, comprise a cylinder onto whichthe web to be printed is fed, and at least a cliché cylinder, onto whichthe printing ink is distributed and from which the ink is transferred tothe web to be printed. In order to obtain the distribution of the inkonto the cliché cylinder, provision is made for a unit, commonly said“colour group”, comprising an ink reservoir, a distributor or “anilox”cylinder receiving the ink from the reservoir and transferring it bycontact to the cliché cylinder, and two blades positioned and actingbetween the ink reservoir and the anilox cylinder. These printingmachines may be provided with more colour groups. Said cliché cylinderis constituted by a smooth cylindrical body onto which a removablejacket is fitted, as a sleeve, said jacket being provided with reliefapt to define the drawings and writes to be printed. Therefore, tochange the prints it is sufficient to remove the jacket from the clichécylinder and substitute it with a different one. Hereinafter, the saidjacket will be also referred to as “cliché-jacket”.

The operation described above usually involves all the colour groups ofthe printing machine. The latter, during the cliché-jacket substitution,must be stopped and it is cause for production loss, this inconvenientbeing as more evident as higher is the time required to operate saidsubstitution.

In order to substitute the cliché jacket, it is necessary to slightlyexpand the latter to allow an easier extraction thereof. At this end,the cliché cylinder is provided with an air inlet to which an end of aduct is manually connected, the said duct being connected to an aircompressor. The compressed air thus entering the cylinder escapesthrough a plurality of radial holes provided within the same cylinder,causing the jacket expansion and thus facilitating its extraction, i.e.removal. Once executed the jacket substitution, the compressed air flowis interrupted and, before to restart the machine, it is necessary todisconnect the compressed air feeding duct from the cylinder. Theseoperations are performed with the cylinder being stopped and in a“cantilever” position, i.e. locked in correspondence of its motor sideend, the transmission side end of the cylinder being free to allow theextraction and subsequent remounting of the cliché jackets by movingthem along the cylinder axis, starting from the operator side of thelatter. Since the operator first has to connect the compressed air ductand then remember to disconnect it before to re-start the machine, maybe cause for injuries to the operator and damages to the machine. Infact if said duct is not disconnected after having substituted thecliché-jacket and before to re-start the machine, the duct, the cylinderand other parts of the machine may be subject to breaking and therespective fragments may provoke injuries to the operator.

The main aim of the present invention is to avoid the above mentioneddrawbacks.

This result has been achieved, according to the present invention, byadopting the idea to realize a device and a method having thecharacteristics described in the independent claims. Furthercharacteristics of the present invention are the object of the dependentclaims.

Thanks to the present invention, it is possible to highly increase thejob safety and highly reduce the risk of damages for the machine.Furthermore, the present invention makes it possible to reduce the timerequired to substitute the cliché-jacket and, consequently, to reduceproduction losses, this being even more evident if one considers thehigh number of distributor groups normally involved. Furthermore, adevice according to the present invention is relatively easy to make, issafe and easy to operate, and it is reliable even after a prolongedservice time.

Examples of the present invention will now be described in detail withreference to the accompanying drawings, in which:

FIG. 1 is a schematic longitudinal section view of a cliché cylinderprovided with a device according to a possible embodiment of the presentinvention shown in an operative state;

FIG. 2 refers to the example shown in FIG. 1 with the cliché cylinder inan inoperative state, that is, positioned in such a manner to allow thesubstitution of the cliché jacket;

FIGS. 3 and 4 show, as in FIGS. 1 and 2, a device according to a furtherembodiment of the present invention;

FIG. 5 is an enlarged detail of FIG. 1;

FIG. 6 is a simplified block diagram of the control system.

Although the present invention will be described with reference to theembodiments shown in the drawings, it should be understood that thepresent invention can be embodied in many alternate forms ofembodiments.

Generally speaking, a device according to the present invention can beused for the removal of a jacket from a cliché cylinder in a printingmachine or similar. In this type of machine, said cylinder is motorizedto drive it into rotation about its own longitudinal axis, and isprovided with an inlet connectable, on one side, to a compressed airsupply and, on the other side, to a plurality of radial holes crossingthe cylinder and utilizable to obtain a deformation of the jacket fittedon the cylinder. The device according to the invention comprises: meansfor automatically connecting said inlet to a delivery means connected tosaid compressed air supply; and means for sensing the position of saidinlet relative to said delivery means apt to allow their precise andautomatic positioning in a reciprocal coupling position.

In the enclosed drawings, the cliché cylinder is designated by thereference numeral 1, the cliché jacket is designated by the referencenumeral 2 and the frame (fixed structure) of the machine is designatedby the reference numeral 9. Furthermore, in the following descriptionthe wording “operator side” means the side of the machine from which anoperator can extract the cliché jacket from a corresponding cylinder andsubstitute it with another cliché jacket, while “transmission side”means the side of the machine opposed to the operator side, that is, theside of the machine in correspondence of which are positioned the motorsdriving the rotation of the cylinder cylinders and eventually drivingthe rotation of further cylinders not shown in the drawings. A clichécylinder is, as said before, a cylindrical body whose surface is smoothor substantially smooth, onto which a tubular jacket provided withrelief is fitted. Said tubular jacket is referred to as “cliché jacket”(independently by the fact that the substance to be distributed be inkor other). The cliché cylinder is provided with an air inlet which isconnected, in a per se known manner, to a plurality of radial holesprovided within the cylinder: compressed air entering said cylinderthrough said air inlet flows through said radial holes from the insideto the outside of the cylinder.

Referring to FIGS. 1 and 2, the cliché cylinder 1 is connected to acorresponding electric motor 3 which drives the cylinder into rotationabout the respective longitudinal axis. The cliché cylinder 1 is of thetype constituted by a cylindrical body having a smooth or substantiallysmooth surface, onto which a cliché jacket is fitted. The clichécylinder 1 is provided with a shaft whose ends 10 and 11 develop towardsthe operator side and respectively the transmission side of the machine.The ends 10 and 11 of said cylinder are respectively supported by anoperator side support 12 and a transmission side support 13. The support12 and the support 13 are provided with respective roller bearings, of aknown type, that is of the type wherein the external ring can axiallymove with respect to the internal ring.

A terminal portion 14 of said end 11 is shaped as a toothed shaft, sothat it realizes a portion of the cylinder 1 cinematically connected tothe motor 3 through the respective shaft 31 and a corresponding groovedjoint 32. In practice, according to a per se known mechanical scheme,said portion 14 receives the motion from the shaft 31 of the motor 3 andis allowed to longitudinally slide within the joint 32.

A sleeve 42 solid to the shaft of the cylinder 1 is provided, onto amiddle portion of the said end 11, in a position between said terminalportion 14 and the portion resulting inside the support 13. Said sleeve42 is internally provided with a bearing 43 through which acorresponding portion of the cylinder 1 shaft passes. Furthermore, anupper portion 44 of the sleeve 42 is provided with a threading 45.

The frame 9 of the machine also supports a second electric motor 4 whoseoutput shaft 40 is solid to an element provided with a threaded rod 41engaging the threading 45 of said sleeve 42. In practice, said element,with the relevant threaded rod 41, constitutes an axial prolongation ofsaid shaft 40. The operation of the motor 4 determines the rotation ofits output shaft 40 and, consequently, the screwing or unscrewing(depending on the rotation direction) of the threaded rod 41 within thethreading 45 of the sleeve 42. Said screwing or unscrewing are cause forthe axial movement of the sleeve 42 and of the shaft to which it issolid, i.e. the translation of the cylinder 1 relative to the frame 9 ofthe machine, with contemporary sliding of the above-mentioned toothedshaft within the joint 32.

The frame 9 of the machine is also provided with a device apt to performa “cantilever” locking, to be used to lock the shaft of the cylinder 1during the extraction and the substitution of the cliché-jacket 2 asbetter described below.

To obtain said cantilever locking of the cylinder 1, it can be used, forexample, an actuator 5 supported by the frame 9 on the transmission sideof the machine and whose stem 50 is oriented radial with respect to theshaft to be locked, in such a manner to lock said shaft when theactuator 5 is activated. When the stem 50 of the actuator 5 isextracted, the shaft of the cylinder 1 is locked on the transmissionside, so that the cliché-jacket 2 can be extracted from the opposedside, i.e. from the operator side, after having removed or disassembledthe support 12. During operation, i.e. during printing, the said stem 50is retracted and the shaft of the cylinder 1 bears on both therespective supports 12 and 13, free to rotate about its longitudinalaxis, the rotation being driven by the motor 3.

In the drawings, the block 6 denotes a compressed air supply, which isconnected to a supply duct 61, the latter being provided with anelectric on-off type valve 60. When the valve 60 is on, the compressedair flows through the duct 61.

The duct 61 is connected to the delivery means 8 which, in the exampleshown in the drawings, is a tubular body whose distal end 80 is shapedas a disc orthogonal to the longitudinal axis of the delivery means 8.The inner side, i.e. the side facing the cylinder 1, of said disc-shapedend 80 is provided with one or more seal rings 84, for example rubberrings. The tubular body 8 is supported by the frame 9 of the machine andis positioned in a sleeve 62 which, in turn, is fixed to a support 65solid to the frame 9. A spring 63 is positioned between said disc-shapedend 80 and said support 65, the said spring being intended to keep thedisc-shaped end 80 spaced from the support 65. A ring-shaped stop 82 isprovided on the tubular body of the delivery means 8, said stop beingpositioned on opposite side of the spring 63 with respect to the sleeve62.

The sleeve 62, the delivery means 8 and the spring 63 are coaxial toeach other and their common axis is parallel to the rotational axis ofthe cylinder 1.

The cylinder 1 is provided, in correspondence of its transmission sidebase 140, with an air inlet 7. The longitudinal axis of said air inlet 7and said body 8 are equidistant from the rotational axis of the cylinder1.

When the cliché-jacket 2 is to be substituted, the cylinder 1 isautomatically positioned in a position where the air inlet 7 and thedelivery means 8 are coaxial, then the cylinder 1 is translated towardsthe transmission side and, subsequently, the device 5, 50 is activatedthe lock the cylinder 1 in the cantilever position. The above steps areautomatically performed, according to the procedure whose steps arefurther described below, on command given by the operator.

As said before, means are provide to sense the position of said airinlet 7 relative to the delivery means 8. For example, said means maycomprise an encoder or the like connected to shaft of the cylinder 1 orto any element cinematically connected to this shaft. In practice,reference being made to the example shown in the drawings, since theangular position of the delivery means 8 with respect to thelongitudinal/rotational axis of the cylinder 1 is known, the support ofthe delivery means being solid to the frame of the machine, it issufficient to sense the angular position of the air inlet 7 only. Toobtain the coaxial positioning of the said air inlet 7 relative to thedelivery means 8, the cylinder 1 is rotated by the motor 3 until theangular positions of the air inlet 7 and the delivery means 8 arecoincident (air inlet 7 and delivery means 8 coaxial). To this end, themotor 3 is connected to a programmable electronic unit E, shown in formof a rectangular box in the drawings, which, in turn, is connected tosaid sensing means from which it receives signals corresponding to theangular position of the cylinder 1 and, consequently, of its air inlet7. The unit E drives the motor 3 until the air inlet of the cylinder andthe compressed air delivery means are coaxial. When this operativecondition is reached, the unit E stops the motor 3. Then, the unit Eactivates the motor 4, thus causing a preset translation of the cylinder1 towards the machine transmission side. This is obtained, as saidabove, by the screwing the of the rod 41, driven by the motor 4, withinthe threading 45 of the sleeve 42 which is solid to the shaft of thecylinder 1. The movement of the cylinder 1 (right-side translation inthe drawings) determines the contact between the outlet of the deliverymeans 8 and the air inlet 7. The contact between the air inlet 7 and thedelivery means 8 is improved thanks to the spring 63 and the rings 84provided by the disc-shaped end 80. Since the overall geometry and thedimensions of each element of the system are known, the length of thesaid translation to which the cylinder 1 is subject is a known andpreset length.

Further sensing means are provided, to sense the length of saidtranslation involving the cylinder 1, including an optical or mechanicalswitch or the like provided in a preset position along the axial pathfollowed by the cylinder, apt to send an electric signal, eventuallywith a preset late, to said on-off valve 60. The latter is normally off,i.e. is off when the printing machine is operative. Said sensing means,which are connected to said unit E, can sense the position of the sleeve42, or the position of the delivery means 8, or the position of everyother element which is subject to said axial movement.

When the air inlet 7 of the cylinder 1 is in contact with the deliverymeans 8, the actuator 5 is activated to cylinder 1 in the cantileverposition and the on-off valve 60 is switched on. Therefore, compressedair flows along the path defined by the duct 61, the delivery means 8and the air inlet 7, reaching the radial holes provided within thecylinder, so that the cliché-jacket 2 is expanded and it may beextracted after having removed or disassembled the operator side support12.

Thereafter, another cliché-jacket is fitted onto the cylinder, theon-off valve 60 being still in the on state. Finally, the valve 60 isswitched off, the support 12 is remounted and the actuator 5 isdeactivated. Then, the motor 4, by rotating in opposite direction withrespect to the previous one, determines the axial movement, i.e.translation, of the cylinder 1 towards the operator side, until thenormal operative position of the cylinder is reached. With reference toFIGS. 3 and 4 of the appended drawings (where the same elements shown inFIGS. 1 and 2 are denoted by the same reference numerals), the deliverymeans 8 is connected, by means of a corresponding bracket 100, to alinear actuator 101, the latter being solid to the frame 9. Said linearactuator drives the translation of said delivery means from and to thecylinder 1, so that the approach of the delivery means to the air inlet7 of the cylinder 1 (as shown in FIG. 4) is obtained by simply movingthe delivery means forwards (left-side direction in the figure). Whenthe cliché-jacket is to be substituted, the same procedure describedabove is performed, with the exception that the contact between the airinlet 7 of the cylinder 1 and the delivery means 8 is obtained bytranslating the delivery means 8 forwards (the translation directionbeing parallel to the rotational axis of the cylinder 1) instead oftranslating the cylinder 1 backwards. The compressed air flow isactivated, through the valve 60, with a preset late after havingactivated the actuator 101 or, by providing a limit switch (for sake ofclarity not shown in the drawings) in a preset point along the pathfollowed by the delivery means 8, when the limit switch senses that thedelivery means 8 reaches a position in which there is the contactbetween the air inlet 7 and the delivery means 8.

A method according to the present invention comprises the followingsteps: sensing the position of said air inlet 7 relative to a deliverymeans connected to a compressed air supply 6; positioning said air inlet7 in correspondence of said delivery means 8, that is, in a positionwhere the air inlet 7 and the delivery means 8 are coupled, by means ofcontrolled rotation of the cylinder 1 about its longitudinal axis andreciprocal approaching of the air inlet 7 and the delivery means 8;supplying compressed air through said delivery means 8 when it iscoupled to said air inlet 7; extracting the cliché-jacket 2 from thecylinder 1 when the cliché-jacket is expanded by the compressed airflowing through said delivery means 8 and through a plurality of radialholes which are provided by the cylinder 1 and are connected with saidair inlet 7.

From the above it is evident that any risk for the operator and for themachine is drastically reduced. At the same time, since the positioningdescribed above is automatic, the time required to substitute acliché-jacket are drastically reduced.

The elements driving the movements, command and control of thecomponents described above are known to the technicians of theindustrial automation and, therefore, they are not described in furtherdetail. It will therefore be readily understood by those persons skilledin the art that the present invention is susceptible of broad utilityand application. Many embodiments and adaptations of the presentinvention other than those herein described, as well as many variations,modifications and equivalent arrangements, will be apparent from orreasonably suggested by the present invention and the foregoingdescription thereof, without departing from the substance or scope ofthe present invention. Accordingly, while the present invention has beendescribed herein in detail in relation to preferred embodiments, it isto be understood that this disclosure is only illustrative and exemplaryof the present invention and is made merely for purposes of providing afull and enabling disclosure of the invention. The foregoing disclosureis not intended or to be construed to limit the present invention orotherwise to exclude any such other embodiments, adaptations,variations, modifications and equivalent arrangements, the presentinvention being limited only by the claims appended hereto and theequivalents thereof.

1. A device for the substitution of a cliché-jacket from a clichécylinder in a printing machine or the like wherein said cylinder isconnected to a motor driving said cylinder into rotation about alongitudinal axis thereof and said cylinder is provided with radialholes connected with an air inlet, said air inlet being apt to beconnected with a compressed air supply by means of a delivery means, thedevice comprising: an automatic means for sensing the position of saidair inlet relative to said delivery means and automatic means forpositioning said air inlet and said delivery means in a reciprocalcoupling position, said automatic sensing and positioning means beingconnected to a programmable electronic unit which, when said air inletand said delivery means are coaxial, drives said coupling and switcheson an on-off valve which, on a side, is connected to said compressed airsupply (6) and, on another side, is connected to said delivery means. 2.A device according to claim 1, wherein said delivery means is in a fixedand preset position.
 3. A device according to claim 1, wherein saidautomatic means for positioning the air inlet of the cylinder in acoupling position with said delivery means comprises a means for axiallytranslating said cylinder.
 4. A device according to claim 3, whereinsaid means for moving said cylinder comprises a motor acting on a sleevelinked to the cylinder.
 5. A device according to claim 1, wherein saiddelivery means comprises a tubular body having a disc-shaped distal endwhich is orthogonal to the longitudinal axis of the tubular body.
 6. Adevice according to claim 5, wherein the external side of saiddisc-shaped end is provided with one or more sealing rings, saidexternal side facing said cylinder.
 7. A device according to claim 5,further comprising an elastic means for exerting on said tubular body aforce directed towards the cylinder.
 8. A device according to claim 1,wherein said on-off valve is positioned and acts along a duct connectedto said compressed air supply.
 9. A device according to claim 1, whereinsaid delivery means is connected to corresponding moving means.
 10. Amethod for substituting the cliché-jacket on a cliché cylinder in aprinting machine or the like wherein said cylinder is motorized so thatsaid cylinder is driven into rotation about a longitudinal axis thereofand said cylinder is provided with a compressed air inlet which isconnectable to a compressed air supply and said compressed air inlet isconnected to a plurality of radial holes going through the cylinder andusable to obtain a deformation of the cliché-jacket fitted onto thecylinder, the method comprising the following automatic steps: providinga delivery means; providing a device comprising an automatic means forsensing a position of said air inlet relative to said delivery means andan automatic means for positioning said air inlet and said deliverymeans in a reciprocal coupling position, said automatic sensing meansand said automatic positioning means being connected to a programmableelectronic unit, said programmable electronic unit driving the couplingof said air inlet and said delivery means and said programmableelectronic switching on an on-off valve when said air inlet and saiddelivery means are coaxial, said on-off valve being connected on oneside to said compressed air supply, said on-off valve being connected tosaid delivery means on another side; sensing the position of said airinlet with respect to said delivery means connected to said compressedair supply with said automatic sensing means; positioning said air inletin correspondence of said delivery means; coupling said air inlet withsaid delivery means; and supplying compressed air through said deliverymeans.
 11. A method according to claim 10, wherein said delivery meansis in a fixed and preset position, wherein said positioning of the airinlet relative to the delivery means is obtained by rotating thecylinder about said longitudinal axis and approaching the cylinder tothe delivery means through an axial translation of the cylinder.
 12. Amethod according to claim 11, further comprising sensing the axialposition of the cylinder before supplying the compressed air.
 13. Amethod according to claim 10, wherein said positioning of the air inletrelative to the delivery means is obtained by rotating the cylinderabout said longitudinal axis and approaching the delivery means to thecylinder through an axial translation of the delivery means.
 14. Adevice for the substitution of a cliché-jacket from a cliché cylinder ina printing machine, the device comprising: a motor; a cylinder connectedto said motor, said motor driving said cylinder into rotation about alongitudinal axis thereof, said cylinder comprising radial holes and anair inlet, said radial holes being in communication with said air inlet;a compressed air supply; a delivery means for delivering compressed airfrom said compressed air supply to said air inlet; an automatic sensingmeans for sensing a position of said air inlet relative to said deliverymeans; an automatic positioning means for positioning said air inlet andsaid delivery means; an on-off valve, one side of said on-off valvebeing connected to said compressed air supply, another side of saidon-off valve being connected to said delivery means; a programmableelectronic unit connected to said automatic sensing means and saidautomatic positioning means, said programmable electronic unitcontrolling said automatic positioning means such that said air inlet iscoupled with said delivery means when said automatic sensing meanssenses said air inlet is coaxial with said delivery means, saidprogrammable electronic unit switching on said on-off valve when saidair inlet is coupled with said delivery means.